Aluminum-silicon (Al—Si) alloy may be produced by melting aluminum and heating the molten aluminum to above 1200° C. Silica (SiO2) may then be added in the form of quartz fines or sand and mixed into the molten aluminum for 30 to 120 minutes. By superheating the molten aluminum to temperatures greater than 1200° C., the overall temperature of molten aluminum when combined with silica can reach the target reaction temperature of about 1150° C. This heat allows for the reduction of silica with the molten aluminum and results in an aluminum-silicon alloy as well as a by-product slag of silica and aluminum oxide (Al2O3). The slag, being heavier (i.e., more dense) than the molten aluminum silicon-alloy, separates from the alloy and sinks to the bottom of the molten bath where it is removed. The aluminum-silicon alloy so produced may then be further processed into more purified forms of silicon for use in chemical, solar, or semiconductor applications.
However, for current heating processes such as the use of an induction furnace, in order to achieve the desired temperature for the reaction of silica, the molten aluminum must be excessively heated (i.e., superheated). This results in losses of aluminum as vapor produced by the excessive heating. Furthermore, because silica is less dense than aluminum, the added silica tends to float on top of the molten aluminum, making mixing difficult and inhibiting the overall reaction between the silica and the molten aluminum. Stirring the mixture is difficult because of this tendency of the silica to float and because the high temperature resistant mixing blades, typically fabricated of graphite, are brittle and tend to fail because of the shear stresses generated during mixing. Finally, the by-product slag (typically Al2O3 and SiO2) has a high melting temperature and the solid slag particles can capture some of the aluminum-silicon alloy as the slag sinks to the bottom of the molten bath. The by-product slag also can adhere to the furnace refractory lining, forming a difficult to remove crust. Because of these inefficiencies in current processes, the utilization of aluminum in reducing silica and forming an aluminum-silicon alloy is only about 50%. That is, only about one-half of the original aluminum alloys with silicon; the remainder is lost as vapor, slag, or captured by separation of the slag. Because aluminum represents a significant portion of the overall cost of the process, there remains a need to provide a more efficient method for producing aluminum-silicon alloys.